In healthy individuals, insulin release by the pancreas is strictly coupled to the blood glucose concentration. Elevated blood glucose levels like those occurring after meals are rapidly compensated by a corresponding rise in insulin secretion. Diabetes mellitus, or simply diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the pancreas does not produce enough insulin, or because cells do not respond to the insulin that is produced. Around 366 million people worldwide suffer from diabetes mellitus. Untreated, diabetes can cause many complications. Acute complications include diabetic ketoacidosis and nonketotic hyperosmolar coma. Serious long-term complications include cardiovascular disease, chronic renal failure, diabetic retinopathy, and diabetic neuropathy. The adequate treatment of diabetes is thus important and there is a need for improved therapies for the treatment of diabetes.